Evidence of a new ordered vacancy crystal structure in the compound Cu3In7Te12

The crystal structure of the ordered vacancy compound (OVC) Cu3In7Te12 is analyzed using powder X-ray diffraction data. It is found that this OVC crystallizes with a chalcopyrite-related structure, in the tetragonal space group P 4 2c (No 112), with unit cell parameters and volume a = 6.1720(2) A, c = 12.3597(8) A, and V = 470.83(4) A3. The Rietveld refinement of 28 instrumental and structural parameters led to Rp = 9.27 %, Rwp = 10.30 %, Rexp = 6.95% and S = 1.48, for 4501 step intensities and 130 independent reflections, respectively. This compound is isostructural with Cu3In7Se12, and has a defect adamantane structure. Keywords: semiconductors, ordered vacancy compounds, crystal structure, X-ray diffraction, Rietveld.